Kiwi_Roy

The Starter solenoid draws a lot of current 40 - 50 Amps so it will blow a 15 Amp fuse after a few seconds. Actually on most Guzzi's the solenoid current is limited by bad joints dirty contacts and wimpy wires.

Thats right the tiny ground wire will get red hot and weld itself to other wires in the loom This happens while cranking up to 150 Amps, there's a photo on here somewhere

The dimmer switch will drop the Voltage to the headlight by quite a bit. I usually add a relay or pair of relays in the headlight bucket If you use a form C relay powered up at the common terminal one filament on N/O one on N/C then you only need one signal from the dimmer switch The dimmer switch now has an easy life switching about 100 milliamps rather than 4-5 Amps There can be a considerable loss of Voltage between the headlight relay and the headlight bucket. I read somewhere that incandescent Lamp brightness is effected by voltage to the power of 5 Note Voltage drop in the headlight circuit also effects battery charging if you have a Ducati Energia regulator, it taps into the headlight feed after the relay up under the tank I'm talking early VII Sport.

This chart is enlightening I don't think Flooky told us what battery he has? Probably not an Odyssey i'm guessing. Isn't the normal battery Guzzi's come with a Yuasa, we need a decent chart similar to Odyssey's for that make. Roy

I like the switch feature, please attach a link to the Amazon advert. A Voltmeter is good for peace of mind, I bought a new V7 in 2017 with a short in the stator, struggled for weeks with weak charging before the stator was replaced under warranty but now with a Voltmeter I can relax. I have mine connected to the running light in the headlight bucket. On with the key.

I remember in early days with my VII Sport when the regulator failed flattening the battery, I went to a local electronics part shop where I purchased a potted bridge rectifier connected the two yellow wires to AC terminals negative to chassis and Positive to battery. Rode home keeping the revs low so it didn't cook the battery. https://www.amazon.ca/BOJACK-KBPC2504-Rectifier-Electronic-Silicon/dp/B07X8G6CPX/ref=asc_df_B07X8G6CPX These need to be bolted to a heat sink for cooling. Beats calling for a tow.

It sounds like time to purchase a new ignition switch, What is the mileage on the bike? Do the lights turn ON with the key? another possibility, use a 12 Volt relay connected to the good remaining contact to bypass the ignition switch. Shortly after buying a used VII Sport I had it splutter and die I suspected the ignition switch and found the contact resistance to be over 18 Ohms so I pulled the switch apart, the grease in the contacts was quite stiff holding the contacts apart, wiped it all out and replaced with fresh, soft, Vaseline This should be done every year or so. The Key mechanisms are sometimes very hard to remove, if so you can sometimes just unscrew the contact block. I wonder if you could just shim the lock barrel using shim stock? Sometimes the wires snap off where they are soldered to the switch the switch due to the constant flexing back and forth, the copper wires work harden and becomes brittle. Try to clamp the wires so they don't flex next to the solder joint. If you can re-locate the switch from the steering to the frame somewhere so there is no wire flexing that's an improvement.

You could swap the coils over but you have to swap the primary wires also If you measure the resistance from the plug cap to chassis it should be the same on both sides about 7000 Ohms from memory might be less if there's no suppressor resistor in line.

I would also check that you're not losing Voltage through a dirty ignition switch that happened to my VII Sport cleaning and re-lubing the switch fixed that.

To make your bike more visible to other road users consider adding a pair of LED driving lights I added a pair of these to my V7III Special $40 each https://www.superbrightleds.com/led-light-pod-2-modular-led-off-road-work-light-10w-900-lumens The nice thing about LEDs they normally give out full brightness from 9 Volts on up so you can lose a Volt you can't afford to lose with an incandescent lamp These lights come with an integral cable about a foot long so you may not need the optional wiring Harness.

Yes, make sure your main ground is good, typically it runs to a 6mm bolt at the rear of the gearbox The regulator also needs to be well grounded, i prefer that to be a short jumper to a timing cover screw rather than back to the battery. I think we figured that this picture was the result of a bad main ground,. On starting the starter current 100+ Amps tried to get back to the battery via the small wire between the regulator case and battery Negative the massive engine and gearbox castings are a better path than a wimpy copper wire. Better that the starter doesn't work than frying the loom.

CIty Light The small bulb in the headlight Park Light or any low load circuit that's on with the key

Its good to have a nice multimeter in the garage but at the price of these things why not have it on the bike 24/7 where you can see it while riding https://www.walmart.ca/en/ip/Digital-Voltmeter-Mini-LED-Round-Battery-Tester-12-Volt-24-Volt-Voltage-Meter-Waterproof-for-Car-Motorcycle-Boat-1-Piece-Red/61I6RYXP96V5 From this vendor the price is $25 but I have seen it several sites for $6 so shop around. I have one on my V7III connected across the city light, best mod ever. https://www.amazon.ca/Waterproof-Voltage-Digital-Voltmeter-Motorcycle/dp/B09MZHJQJX/ref=asc_df_B09MZHJQJX?th=1 They even ship it with a pair of spade connectors to wire it up fo $6 I prefer the blue colour LED over amber. The case is waterproof. When I turn the key On it shows 12.5 - 12.6, drops down to ~10.5 while cranking then jumps up to 13, will sometimes go as high as 14.2 while motoring at speed

Sherly you guys are not still having relay trouble???? I thought that issue was long gone Roy Moto Guzzi - making Electricians out of riders since 1921

Molly, Many owners have gone before you, the wiring is a weak point on Guzzis, I went through a failed regulator and broken wires inside the alternator also Roy

This is another weak point, my VII sport failed there as well. don't try to re-attach the copper will be corroded, just replace both wires back to the regulator. Note, the bullet connectors at the regulator are not a standard size you would be better off crimping the wires there with a suitable size of crimp link. Roy

I see here you are testing the diodes (meter switch to the diode position that's about the only testing you can do. If by chance you find that one of the diodes is open circuit its possible to add a new diode outside the case the circuit just goes Yellow wire through the diode to the regulator case. You still need the yellow to go to the internal circuit it's part of a bridge rectifier a pair of diodes and a pair of Silicon controlled rectifiers. I used to have a circuit diagram I drew of the regulator but I have misplaced it. If you reverse the leads the meter shows Open circuit right? When it failed I think the battery was flat (no fuel, No spark) When you put the regulator back on the case has a good connection to chassis? looking at the male/female connection to the loom where the regulator plugs inwith the key On you see +12V on the female to chassis? it is the power supply and voltage reference tapped off the headlight supply wire under the tank the male plug of the M/F connector gets the voltage it needs to work from there. Clean the ignition switch, look up from underneath you will see two phillips screws holding the switch block to the lock, take those out and the block will come away in your hand prise it apart and clean out the old grease, replace with new soft Vaseline. Good Luck Roy

The LED will not light up if the fuse holder is loose only if it melts

This topic has been thrashed to bits. The 30 Amp fuse holders do overheat, mine got so hot the fuse welded in place I remember as an apprentice when crimp lugs first came out the inspector might ask you to solder the lug after crimping I doubt anyone does that these days. I advocate dipping the bare wires in Vaseline before crimping this ensures the copper doesn't corrode if the joints get wet A short length of heat shrink tubing over the lug and end of the insulation to keep water out. If you use white heat shrink you can identify the wire with an indelable pen before shrinking it down with hot air gun making it easier to troubleshoot. When I re-wired my 72 Eldorado I used all black wires and identified them this way. https://www.amazon.ca/STAEDTLER-Lumocolor-Superfine-Permanent-Waterproof/dp/B00R64NE42/ref=asc_df_B00R64NE42?

the 30 Amp fuse melting is caused by resistance. heat is caused by resistance x the current squared sometimes this will weld the fuse in place. in this case it has melted the plastic, it might have also taken any tension out of the contacts in which case you may have to provide a new fuse holder. I seem to recall this was a common fault when I first started posting on this site years ago and i may have had the problem on my VII Sport

+100 for Carl's drawings, the first thing I do when trying to troubleshoot from symptoms described is open up the appropriate drawing by Carl Allison http://www.thisoldtractor.com/guzzi007/sportissimo.html Roy

I seem to recall there is something weird about the lamp holders on the VII Sport I remember when I first tried replacing the lamps zi found an equivalent size LED, put them in and found it blew the fuse. The two lamp contacts are not designed for lamps where the contact is on both sides. I was able to snip the wire off one side but when using the 194 lamps you throw away this problem lamp holder and solder the wires directly to the lamp thus eliminating a potential short circuit and making the connection reliable. For the low fuel light I soldered a couple of wires to one of the original lamps covered it with heat shrink and soldered it in parallel with the 194 LED. How do we edit a post, I always seem to see a mistake the second after posting? I see click on the 3 dots and you get an edit option ...

Just reading through this old thread I started. I still maintain the pulse input speedometer is better than GPS, the gearbox has a speedo drive coupled to the rear wheel turning without much friction so why not use it? I do understand wanting to use modern GPS but what will happen when your fearless leader decides to turn the navigation satellites off, he's crazy enough to do that. He won't be able to turn my Speedo off. Once it's calibrated you're done all you need is a measured distance, they used to have them on the highway but I used a runners GPS for that. Cheers Roy